Thruster with segmented propellant

Abstract

A thruster includes multiple segments of electrically-operated propellant, electrodes for igniting one or a few of the electrically-operated propellant segments at a time, and a propellant feeder for moving further propellant segments into engagement with the electrodes. The segments may be configured to provide equal increments of thrust, or different amounts of thrust. The segments may each include an electrically-operated propellant material surrounded by a sealing material, so as to keep the propellant material away from moisture and other contaminants (and/or the vacuum of space) before each individual segment is to be used. The thruster may be included in any of a variety of flight vehicles, for example in a small satellite such as a CubeSat satellite, for instance having a volume of about 1 liter, and a mass of no more than about 1.33 kg.

What is claimed is: 
     
         1 . A thruster comprising:
 an electrically-operated propellant;   electrodes operatively coupled to the electrically-operated propellant; and   a propellant feeder for moving the propellant relative to the electrodes.   
     
     
         2 . The device of  claim 1 , wherein the propellant feeder includes a push rod that pushes the propellant toward the electrodes. 
     
     
         3 . The device of  claim 2 , wherein the feed mechanism includes a resilient device providing a resilient force to push the propellant toward the electrodes. 
     
     
         4 . The device of  claim 3 , wherein the resilient device is a coil spring. 
     
     
         5 . The device of  claim 1 , wherein the propellant includes multiple propellant segments. 
     
     
         6 . The device of  claim 5 , wherein the segments include segments of different sizes. 
     
     
         7 . The device of  claim 5 , wherein the segments include multiple relatively small segments and multiple relatively large segments that are larger than the relatively small segments. 
     
     
         8 . The device of  claim 7 , wherein the relatively small segments and the relatively large segments are positioned such that at least some of the relatively small segments are consumed before any of the relatively large segments are consumed. 
     
     
         9 . The device of  claim 5 , wherein each of the segments includes a sealing material surrounding a propellant material. 
     
     
         10 . The device of  claim 1 , further comprising a nozzle through which pass pressurized gasses from combustion of the electrically-operated propellant. 
     
     
         11 . The device of  claim 1 , as part of a flight vehicle. 
     
     
         12 . A method of firing a thruster, the method comprising:
 igniting a first electrically-operated propellant segment of a plurality of electrically-operated propellant segments, wherein the igniting including using electrodes of the thruster to ignite the electrically-operated propellant segment;   moving a second electrically-operated propellant segment into engagement with the electrodes; and   subsequent to the moving and to the igniting the first electrically-operated propellant segment, using the electrodes to ignite the second electrically-operated propellant segment.   
     
     
         13 . The method of  claim 12 ,
 wherein the first electrically-operated propellant segment is smaller than the second electrically-operated propellant segment; and   wherein the igniting the second electrically-operated propellant segment produces more thrust than the igniting the first electrically-operated propellant segment.   
     
     
         14 . The method of  claim 12 ,
 wherein the first electrically-operated propellant segment is larger than the second electrically-operated propellant segment; and   wherein the igniting the second electrically-operated propellant segment produces less thrust than the igniting the first electrically-operated propellant segment.   
     
     
         15 . The method of  claim 14 ,
 wherein the first electrically-operated propellant segment is the same size as the second electrically-operated propellant segment; and   wherein the igniting the second electrically-operated propellant segment produces the same amount of thrust as the igniting the first electrically-operated propellant segment.   
     
     
         16 . The method of  claim 12 , further comprising only partially burning one or both of the propellant segments. 
     
     
         17 . The method of  claim 12 , wherein the moving the second electrically-operated propellant segment into engagement with the electrodes is performed by a propellant feeder of the thruster. 
     
     
         18 . The method of  claim 17 , wherein the moving the second electrically-operated propellant segment into engagement with the electrodes is part of moving all unconsumed electrically-operated propellant segments of the plurality of electrically-operated propellant segments. 
     
     
         19 . The method of  claim 18 , wherein the moving the unconsumed electrically-operated propellant segments includes using a control rod of the propellant feeder to push the unconsumed electrically-operated propellant segments toward the electrodes. 
     
     
         20 . The method of  claim 18 , wherein the moving the unconsumed electrically-operated propellant segments includes using a resilient device of the propellant feeder to push the unconsumed electrically-operated propellant segments toward the electrodes.